To achieve higher levels of productivity, a printing system must typically process a higher amount or volume of a print medium in a given time period. In many printing systems, the print medium is provided and handled in sheets. Accordingly, such printing systems with higher productivity levels are required to transport the sheets of print medium at higher rates and with greater levels of reliability. In this regard, it is important to transport the sheets of print medium in a manner that substantially avoids imparting any damage or deformation to the sheets. Deformations present within a sheet of a print medium can cause serious reliability problems in a printing system, such as an inkjet printing system. On the one hand, damaged or deformed sheets may lead to a sheet jam in the machinery of the system. On the other hand, if the sheets of printed medium output from the printing system include any such deformations, this naturally compromises the quality of the output and depending on the degree or extent of the deformations in the printed sheets, those sheets may need to be discarded and re-printed.
There are many sources of defects or errors that may degrade the productivity of a printing system. For example, changes in the environmental conditions can lead to deformation of the sheets as they are being processed, and inappropriate settings in the printing system, such as too much ink or a drying temperature that is too high, can also generate problems. A transport mechanism in the printing system will typically employ an under-pressure or suction for holding sheets of the print medium. If an under-pressure or suction is insufficient, deformations or wrinkles known as “cockling” can occur in the sheets, particularly during drying and/or fixing of an image after a printing operation. These influences or defects may also act in combination, thus making it very difficult to identify a root cause of a problem.